class MemoryBackend in Drupal 8

Defines a memory cache implementation.

Stores cache items in memory using a PHP array.

Should be used for unit tests and specialist use-cases only, does not store cached items between requests.

The functions ::prepareItem()/::set() use unserialize()/serialize(). It behaves as an external cache backend to avoid changing the cached data by reference. In ::prepareItem(), the object is not modified by the call to unserialize() because we make a clone of it.

Hierarchy

• class \Drupal\Core\Cache\MemoryBackend implements CacheBackendInterface, CacheTagsInvalidatorInterface

Related topics

Cache API

Information about the Drupal Cache API

12 files declare their use of MemoryBackend

AssetResolverTest.php in core/tests/Drupal/Tests/Core/Asset/AssetResolverTest.php

Contains \Drupal\Tests\Core\Asset\AssetResolverTest.

BackendChainImplementationUnitTest.php in core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php

BackendChainTest.php in core/tests/Drupal/KernelTests/Core/Cache/BackendChainTest.php

ChainedFastBackendTest.php in core/tests/Drupal/Tests/Core/Cache/ChainedFastBackendTest.php

MemoryBackendTest.php in core/tests/Drupal/KernelTests/Core/Cache/MemoryBackendTest.php

... See full list

File

core/lib/Drupal/Core/Cache/MemoryBackend.php, line 22

Namespace

Drupal\Core\Cache

class MemoryBackend implements CacheBackendInterface, CacheTagsInvalidatorInterface {

  /**
   * Array to store cache objects.
   */
  protected $cache = [];

  /**
   * {@inheritdoc}
   */
  public function get($cid, $allow_invalid = FALSE) {
    if (isset($this->cache[$cid])) {
      return $this
        ->prepareItem($this->cache[$cid], $allow_invalid);
    }
    else {
      return FALSE;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getMultiple(&$cids, $allow_invalid = FALSE) {
    $ret = [];
    $items = array_intersect_key($this->cache, array_flip($cids));
    foreach ($items as $item) {
      $item = $this
        ->prepareItem($item, $allow_invalid);
      if ($item) {
        $ret[$item->cid] = $item;
      }
    }
    $cids = array_diff($cids, array_keys($ret));
    return $ret;
  }

  /**
   * Prepares a cached item.
   *
   * Checks that items are either permanent or did not expire, and returns data
   * as appropriate.
   *
   * @param object $cache
   *   An item loaded from self::get() or self::getMultiple().
   * @param bool $allow_invalid
   *   (optional) If TRUE, cache items may be returned even if they have expired
   *   or been invalidated.
   *
   * @return mixed
   *   The item with data as appropriate or FALSE if there is no
   *   valid item to load.
   */
  protected function prepareItem($cache, $allow_invalid) {
    if (!isset($cache->data)) {
      return FALSE;
    }

    // The object passed into this function is the one stored in $this->cache.
    // We must clone it as part of the preparation step so that the actual
    // cache object is not affected by the unserialize() call or other
    // manipulations of the returned object.
    $prepared = clone $cache;
    $prepared->data = unserialize($prepared->data);

    // Check expire time.
    $prepared->valid = $prepared->expire == Cache::PERMANENT || $prepared->expire >= $this
      ->getRequestTime();
    if (!$allow_invalid && !$prepared->valid) {
      return FALSE;
    }
    return $prepared;
  }

  /**
   * {@inheritdoc}
   */
  public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
    assert(Inspector::assertAllStrings($tags), 'Cache Tags must be strings.');
    $tags = array_unique($tags);

    // Sort the cache tags so that they are stored consistently in the database.
    sort($tags);
    $this->cache[$cid] = (object) [
      'cid' => $cid,
      'data' => serialize($data),
      'created' => $this
        ->getRequestTime(),
      'expire' => $expire,
      'tags' => $tags,
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function setMultiple(array $items = []) {
    foreach ($items as $cid => $item) {
      $this
        ->set($cid, $item['data'], isset($item['expire']) ? $item['expire'] : CacheBackendInterface::CACHE_PERMANENT, isset($item['tags']) ? $item['tags'] : []);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function delete($cid) {
    unset($this->cache[$cid]);
  }

  /**
   * {@inheritdoc}
   */
  public function deleteMultiple(array $cids) {
    $this->cache = array_diff_key($this->cache, array_flip($cids));
  }

  /**
   * {@inheritdoc}
   */
  public function deleteAll() {
    $this->cache = [];
  }

  /**
   * {@inheritdoc}
   */
  public function invalidate($cid) {
    if (isset($this->cache[$cid])) {
      $this->cache[$cid]->expire = $this
        ->getRequestTime() - 1;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function invalidateMultiple(array $cids) {
    $items = array_intersect_key($this->cache, array_flip($cids));
    foreach ($items as $cid => $item) {
      $this->cache[$cid]->expire = $this
        ->getRequestTime() - 1;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function invalidateTags(array $tags) {
    foreach ($this->cache as $cid => $item) {
      if (array_intersect($tags, $item->tags)) {
        $this->cache[$cid]->expire = $this
          ->getRequestTime() - 1;
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  public function invalidateAll() {
    foreach ($this->cache as $cid => $item) {
      $this->cache[$cid]->expire = $this
        ->getRequestTime() - 1;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function garbageCollection() {
  }

  /**
   * {@inheritdoc}
   */
  public function removeBin() {
    $this->cache = [];
  }

  /**
   * Wrapper method for REQUEST_TIME constant.
   *
   * @return int
   */
  protected function getRequestTime() {
    return defined('REQUEST_TIME') ? REQUEST_TIME : (int) $_SERVER['REQUEST_TIME'];
  }

  /**
   * Prevents data stored in memory backends from being serialized.
   */
  public function __sleep() {
    return [];
  }

  /**
   * Reset statically cached variables.
   *
   * This is only used by tests.
   */
  public function reset() {
    $this->cache = [];
  }

}

Members

Name	Modifiers	Type	Description	Overrides
CacheBackendInterface::CACHE_PERMANENT		constant	Indicates that the item should never be removed unless explicitly deleted.
MemoryBackend::$cache	protected	property	Array to store cache objects.
MemoryBackend::delete	public	function	Deletes an item from the cache. Overrides CacheBackendInterface::delete	1
MemoryBackend::deleteAll	public	function	Deletes all cache items in a bin. Overrides CacheBackendInterface::deleteAll
MemoryBackend::deleteMultiple	public	function	Deletes multiple items from the cache. Overrides CacheBackendInterface::deleteMultiple
MemoryBackend::garbageCollection	public	function	Performs garbage collection on a cache bin. Overrides CacheBackendInterface::garbageCollection
MemoryBackend::get	public	function	Returns data from the persistent cache. Overrides CacheBackendInterface::get	1
MemoryBackend::getMultiple	public	function	Returns data from the persistent cache when given an array of cache IDs. Overrides CacheBackendInterface::getMultiple
MemoryBackend::getRequestTime	protected	function	Wrapper method for REQUEST_TIME constant.
MemoryBackend::invalidate	public	function	Marks a cache item as invalid. Overrides CacheBackendInterface::invalidate
MemoryBackend::invalidateAll	public	function	Marks all cache items as invalid. Overrides CacheBackendInterface::invalidateAll
MemoryBackend::invalidateMultiple	public	function	Marks cache items as invalid. Overrides CacheBackendInterface::invalidateMultiple
MemoryBackend::invalidateTags	public	function	Marks cache items with any of the specified tags as invalid. Overrides CacheTagsInvalidatorInterface::invalidateTags
MemoryBackend::prepareItem	protected	function	Prepares a cached item.	1
MemoryBackend::removeBin	public	function	Remove a cache bin. Overrides CacheBackendInterface::removeBin
MemoryBackend::reset	public	function	Reset statically cached variables.
MemoryBackend::set	public	function	Stores data in the persistent cache. Overrides CacheBackendInterface::set	2
MemoryBackend::setMultiple	public	function	Store multiple items in the persistent cache. Overrides CacheBackendInterface::setMultiple
MemoryBackend::__sleep	public	function	Prevents data stored in memory backends from being serialized.